1. Field of the Invention
The present invention relates to a noiseproofing apparatus for a resonant scanner. The resonant scanner is means for deflecting a laser beam and it is primarily used for a laser scanning microscope, a laser beam printer and a bar code reader. The soundproofing device is intended to prevent a sound generated by vibration of the resonant scanner from leaking external to the resonant scanner.
2. Description of the Related Art
Apparatus such as a laser scanning microscope, a laser beam printer and a bar code reader have a unit for deflecting a laser beam. The laser beam deflection unit usually uses a Galvanometer scanner, a polygon mirror or an acousto-optical deflection device (AOM). However, the Galvanometer scanner is low in speed, the polygon mirror has a poor durability and a large external dimension because it uses a wearing part, such as a bearing, and the acousto-optical deflection device has a small deflection angle.
The resonant scanner is laser deflection means which solves these disadvantages. The resonant scanner is superior overall to the laser deflection means such as the Galvanometer scanner in the deflection (scanning) speed and the durability, and a use of the resonant scanner as the laser beam deflection means is been known, for example U.S. Pat. No. 5,048,904.
The resonant scanner deflects the laser beam while it is resonated at a resonance frequency between several hundred Hz and several KHz, and a high speed resonant scanner is driven at a resonant frequency between 2 and 8 KHz. However, since such a relatively high resonant frequency is very close to a natural frequency of a surrounding metal (for example, a case), the resonant scanner may resonate the metal and when the sound is propagated through air, it generates a sound in a band which is most sensible and uncomfortable to a human's sense. Accordingly, the apparatus which uses the resonant scanner generates a very uncomfortable sound (resonant sound) due to the vibration of the resonant scanner and the resonant scanner cannot be used in a vicinity of an apparatus with which a human operates.